Dancing with giants: dynamics of dwarf satellite galaxies

June 14, 2018, Leiden University
The nearby Andromeda galaxy with the Messier 110 dwarf galaxy system right below it. Credit: Leiden University

Dwarf satellite galaxies in the Milky Way perform different dances than researchers initially expected. Marius Cautun from Durham University received a Marie Curie grant to unravel the mysteries of this orbital dance. October 1st 2018 he will start his research at the Leiden Observatory.

Giant like our own Milky Way are surrounded by a large number of fainter galaxies, so called dwarf galaxies. These dwarfs perform a complex orbital dance around their parent galaxies. This dance is somewhat similar to the motion of the Jupiter moons around their giant planet. Theoretical models predicted that this should be composed of randomly oriented elliptical orbits. However, observations now reveal the opposite: most Milky Way all in the same plane and have orbits that are much more circular than expected.

'This is a major problem that lacks an answer', tells Cautun. 'It could signal a fundamental breakdown of the current cosmological model. Or alternatively, that our own galaxy is very atypical: a 1 in a 1000 system.' Studies of  dwarf orbits cannot yet be carried out for other , such as our close neighbor the Andromeda galaxy. Therefore the only option is to examine the Milky Way in more detail.

Cautun hopes his research will deliver ground-breaking new insights into the anomalous dynamics of the Milky Way satellites and uncover the formation history of our galaxy. Cautun will first investigate the phenomena that give rise to the atypical orbits of the satellite galaxies. The satellite galaxies form some distance away from the Milky Way and then are accreted onto the dark matter halo of our own galaxy. 'This accretion of satellites takes place along preferential directions, the so called filaments of the cosmic web. I will study to what extent this process induces correlations in the orbits of satellite galaxies', explains Cautun.

Secondly, current studies have analysed only the orbits of bright Milky Way satellites. However, fainter dwarf satellites must also contain vital clues. Around our galaxy, more than 40 of such examples are known. Using state-of-the-art galaxy formation models, Cautun will perform detailed cosmological simulations to predict the distribution of very faint Milky Way satellites. 'Next, I will compare these model predictions with observations to make an unprecedented test of the current cosmological paradigm. The same simulations are also essential for testing the nature of dark matter and galaxy formation models.'

Explore further: How do you weigh a galaxy? Especially the one you're in?

Related Stories

How do you weigh a galaxy? Especially the one you're in?

June 6, 2018

A new technique for estimating the mass of galaxies promises more reliable results, especially when applied to large datasets generated by current and future surveys, according to a research team led by Ekta Patel at the ...

Hubble displays a dwarf spiral galaxy

August 14, 2017

The subject of this NASA/ESA Hubble Space Telescope image is a dwarf galaxy named NGC 5949. Thanks to its proximity to Earth—it sits at a distance of around 44 million light-years from us, placing it within the Milky Way's ...

Satellite galaxies put astronomers in a spin

July 24, 2014

An international team of researchers, led by astronomers at the Observatoire Astronomique de Strasbourg (CNRS/Université de Strasbourg), has studied 380 galaxies and shown that their small satellite galaxies almost always ...

Recommended for you

HESS J1943+213 is an extreme blazar, study finds

June 21, 2018

An international group of astronomers have carried out multi-wavelength observations of HESS J1943+213 and found evidence supporting the hypothesis that this gamma-ray source is an extreme blazar. The finding is reported ...

'Red nuggets' are galactic gold for astronomers

June 21, 2018

About a decade ago, astronomers discovered a population of small, but massive galaxies called "red nuggets." A new study using NASA's Chandra X-ray Observatory indicates that black holes have squelched star formation in these ...

The Rosetta stone of active galactic nuclei deciphered

June 21, 2018

A galaxy with at least one active supermassive black hole – named OJ 287 – has caused many irritations and questions in the past. The emitted radiation of this object spans a wide range – from the radio up to the highest ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

fthompson495
not rated yet Jun 14, 2018
Galactic halos are displaced dark matter. A galaxy's halo is not a clump of dark matter traveling along with the galaxy. A galaxy's halo is displaced dark matter.

Dark matter is a supersolid that fills 'empty' space and is displaced by visible matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the dark matter. The state of displacement of the dark matter is gravity.

Dark matter ripples when galaxy clusters collide and waves in a double-slit experiment, relating general relativity and quantum mechanics.

There is evidence of the supersolid dark matter every time a double-slit experiment is performed, as it is the medium that waves.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.